1. Technical Field
The invention relates in general to an estimation method and an estimation device, and more particularly to an estimation method for use in an orthogonal frequency division multiplexing (OFDM) system to estimate the inter-carrier interference (ICI) power and the noise power in a channel and an estimation device therefor.
2. Description of the Related Art
In the field of communication, the signal is transmitted from a transmitter to a receiver through a channel. In an orthogonal frequency division multiplexing (OFDM) system, for example, the signals are transmitted by the transmitter of the OFDM system through the channel. In the course of transmitting signals, the signals being transmitted are usually influenced by the inter-carrier interference (ICI) power and the noise power in the channel.
Besides, in a mobile communication system, the velocity of the relative movement between the transmitter and the receiver may introduce Doppler spread in the channel used for signal transmission. At this time, if the system in implemented with the OFDM system, the Doppler spread effect will affect the ICI power, wherein the relative velocity is proportional to the ICI power. In such an OFDM system, when the ICI power dominates (i.e. the ICI power is higher than the noise power) and influences the OFDM system seriously, the system may need to adopt the ICI mitigation mechanism to mitigate the influence of the ICI noise.
However, when the noise power dominates (i.e. the noise power is higher than the ICI power), the influence of the ICI power on the OFDM system becomes relatively smaller. In this case, the performance of the OFDM system could be reduced if the OFDM system also adopts the ICI mitigation mechanism. Hence, the performance of OFDM system can be enhanced by selectively adopting the ICI mitigation mechanism if the ICI power and the noise power in the ICI channel can be estimated. Therefore, how to individually estimate the ICI power and the noise power is still a subject of the industrial endeavor.